FIELD OF THE INVENTION
[0001] The present invention relates to a stator core for a motor and its manufacturing
method.
BACKGROUND ART
[0002] Conventionally, there are ones disclosed in Patent Documents 1, 2 and 3 as illustrated
in Figs. 21 to 24. Fig. 21 is a front main part view illustrating a state of a stator
core attached to a core case by shrink-fitting. Fig. 22 is a front main part view
illustrating the stator core. Fig. 23 is a front main part view illustrating a state
of a stator core attached to a core case by shrink-fitting. Fig. 24 is a sectional
view illustrating a state of a stator core attached to a core case by shrink-fitting.
[0003] In all Figs. 21 to 24, stator core segments 103A, 103B and 103C of stator cores 101A,
101B and 101C of motors are joined to form an annular shape and are received and fixed
by shrink-fitting in core cases 105A, 105B and 105C.
[0004] Where, there is a problem that iron loss increases due to compressive stress generated
in the stator core segments 103A, 103B or 103C at the time of the shrink-fitting so
that output efficiency of a motor comes down.
[0005] To address this, the stator core 101A of Figs. 21 and 22 has slits 101Aa made therein
so as not to generate compressive stress, and the stator cores 103B and 103C of Figs.
22 and 24 have holes 103Ba and 103Ca to reduce compressive stress.
[0006] However, the slits 101Aa and the holes 103Ba and 103Ca make an increase of magnetic
resistance and result in a problem of deteriorating magnetic properties.
[0007] On the other hand, in the case of the slits 101Aa, it is conceivable to compressively
deform contacting portions on the outer peripheral side toward a direction to eliminate
the slits (circumferential direction) by the compressive stress.
[0008] However, only the deformation amount due to the distortion around the contacting
portions on the outer peripheral side results in the small amount of the compressive
deformation of the contacting portions, and it is physically difficult to eliminate
the slit 101Aa.
[0009] Such a problem also exists in stator cores other than a divided- type stator core.
PRIOR ART DOCUMENT
PATENT DOCUMENT
SUMMARY OF THE INVENTION
PROBLEM TO BE SOLVED BY THE INVENTION
[0011] The problem to be solved by the invention lies in that a reduction in compressive
stress by means of slits or holes causes an increase in magnetic resistance and deteriorates
magnetic properties.
MEANS FOR SOLVING THE PROBLEM
[0012] The present invention, in order to reduce compressive stress at a portion having
a high density of magnetic flux without forming slits or holes, characterizes a stator
core for a motor in that the stator core including an annular yoke and teeth protruding
radially inward from an inner periphery of the yoke, an outer periphery of the yoke
attached to an inner periphery of an annular member with a radially inwardly tightening
interference, comprises a circumferentially deformable part formed on a radially outer
peripheral side of the yoke and compressively deformed in a circumferential direction
by the tightening interference; circumferentially facing divided parts formed on a
radially inner peripheral side of the yoke, and each having a dividing line that is
oriented in a radial direction and reaches a portion between the teeth and divided
surfaces that face each other without a gap; and radially facing divided parts formed
between the radially inner and outer sides of the yoke along the circumferential direction
at a predetermined interval, each having divided surfaces that face each other in
the radial direction, and being continuous at one ends with the respective circumferentially
facing divided parts, the divided surfaces moved relative to each other in the circumferential
direction by compressive deformation of the circumferentially deformable part, wherein
the circumferentially facing divided parts are in a state of a compressive stress
being smaller than a compressive stress acting on the circumferentially deformable
part or being zero.
[0013] The present invention characterizes a stator core manufacturing method for manufacturing
a stator core for a motor in that the stator core manufacturing method comprises a
segment processing step of processing a plurality of circumferential stator core segments
divided at the circumferentially pressed divided parts, the circumferentially facing
divided parts, and the radially facing divided parts; and an assembly step of joining
the plurality of stator core segments annularly in the circumferential direction and
attaching the plurality of stator core segments to the inner periphery of the annular
member with the radially inwardly tightening interference, thereby pressing the divided
surfaces of the circumferentially pressed divided parts against each other and facing
the divided surfaces of the circumferentially facing divided parts without a gap in
the circumferential direction.
[0014] The present invention characterizes a stator core manufacturing method for manufacturing
the stator core for a motor in that the stator core manufacturing method comprises
a semi-finished core processing step of forming a semi-finished stator core having
the ring part, circumferentially facing divided part correspondents, and radially
facing divided part correspondents; and an assembly step of attaching the semi-finished
stator core to the inner periphery of the annular member with the radially inwardly
tightening interference, thereby causing compressive deformation of the ring part
and facing the divided surfaces of the circumferentially facing divided parts without
a gap in the circumferential direction.
EFFECT OF THE INVENTION
[0015] Because of the above configuration, the stator core for a motor of the present invention
generates the compressive stress by the attachment to the annular member with the
tightening interference in the circumferentially deformable part on the outer peripheral
side of the yoke, and the circumferentially facing divided parts on the inner peripheral
side of the yoke are put into the state of the compressive stress being smaller than
the compressive stress acting on the circumferentially deformable part or being zero.
[0016] As a result, much of magnetic flux passes through the circumferentially facing divided
parts involving less compressive stress, to realize small magnetic loss such as iron
loss and the stable attachment to the annular member.
[0017] Because of the above configuration, the stator core manufacturing method of the present
invention produces the plurality of stator core segments, annularly joins the plurality
of stator core segments in the circumferential direction, and attaches them to the
inner periphery of the annular member with the radially inwardly tightening interference,
thereby generating the compressive stress based on the tightening interference in
the circumferentially pressed divided parts so that the circumferentially facing divided
parts are put into the state of the compressive stress being smaller than the compressive
stress acting on the circumferentially pressed divided parts or being zero.
[0018] Because of the above configuration, the stator core manufacturing method of the present
invention produces the semi-finished stator core and attaches it to the inner periphery
of the annular member with the radially inwardly tightening interference, thereby
generating the compressive stress based on the tightening interference in the ring
part so that the circumferentially facing divided parts are put into the state of
the compressive stress being smaller than the compressive stress acting on the circumferentially
deformable part or being zero.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019]
[Fig. 1] It is a front main part view illustrating a state of a stator core attached
to a motor case by shrink-fitting. (First embodiment)
[Fig. 2] It is a side view illustrating the stator core at circumferentially pressed
divided parts. (First embodiment)
[Fig. 3] It is a sectional view illustrating a stack of the stator cores. (First embodiment)
[Fig. 4] It is a process chart illustrating a stator core manufacturing method. (First
embodiment)
[Fig. 5] It is a front main part view illustrating stator core segments processed
in a segment processing step. (First embodiment)
[Fig. 6] It is a front main part view illustrating the stator core segments in a joined
state before shrink-fitting in an assembly step. (First embodiment)
[Fig. 7] It is a front main part view illustrating a stator core according to a modification.
(First embodiment)
[Fig. 8] It is a front main part view illustrating a stator core. (Second embodiment)
[Fig. 9] It is a side view illustrating a flexible portion of the stator core. (Second
embodiment)
[Fig. 10] It is a sectional view partly illustrating a stack of the stator cores.
(Second embodiment)
[Fig. 11] It is a side view illustrating a flexible portion of a stator core according
to a modification. (Second embodiment)
[Fig. 12] It is a sectional view partly illustrating a stack of the stator cores according
to the modification. (Second embodiment)
[Fig. 13] It is a side view illustrating a flexible portion of a stator core according
to another modification. (Second embodiment)
[Fig. 14] It is a sectional view partly illustrating a stack of the stator cores according
to the modification. (Second embodiment)
[Fig. 15] It is a side view illustrating a flexible portion of a stator core according
to still another modification. (Second embodiment)
[Fig. 16] It is a sectional view partly illustrating a stack of the stator cores according
to the modification. (Second embodiment)
[Fig. 17] It is a front main part view illustrating a state of a stator core attached
to a motor case by shrink-fitting. (Third embodiment)
[Fig. 18] It is a process chart illustrating a stator core manufacturing method. (Third
embodiment)
[Fig. 19] It is a front main part view illustrating a state of a semi-finished stator
core before shrink-fitting. (Third embodiment)
[Fig. 20] It is a front main part view illustrating a state of a stator core according
to a modification attached to a motor case by shrink-fitting. (Third embodiment)
[Fig. 21] It is a front main part view illustrating a state of a stator core attached
to a core case by shrink-fitting. (Prior art)
[Fig. 22] It is a front main part view illustrating the stator core. (Prior art)
[Fig. 23] It is a front main part view illustrating a state of a stator core attached
to a core case by shrink-fitting. (Prior art)
[Fig. 24] It is a sectional view illustrating a state of a stator core attached to
a core case by shrink-fitting. (Prior art)
EMBODIMENTS FOR CARRYING OUT THE INVENTION
[0020] The object capable of reducing compressive stress without forming slits or holes
is accomplished by a stator core that is provided with a circumferentially deformable
part, circumferentially facing divided parts, and radially facing divided parts.
FIRST EMBODIMENT
[0021] Fig. 1 is a front main part view illustrating a state of a stator core attached to
a motor case by shrink-fitting, Fig. 2 is a side view illustrating the stator core
at circumferentially pressed divided parts, and Fig. 3 is a sectional view partly
illustrating a stack of the stator cores.
[0022] As illustrated in Figs. 1 to 3, a stator core 1 is made of a magnetic steel plate
and has an annular yoke 3 and teeth 5 protruding radially inward from an inner periphery
of the yoke 3. A plurality of stator cores 1 are stacked one on another, and an outer
periphery of each yoke 3 in the stacked state is attached to an inner periphery of
a motor case 7 as an annular member by shrink-fitting with a radial inward tightening
interference.
[0023] The yoke 3 is provided with circumferentially pressed divided parts 9, circumferentially
facing divided parts 11, and radially facing divided parts 13.
[0024] The circumferentially pressed divided parts 9 are formed in a circumferentially deformable
part 14 on a radially outer peripheral side and each have dividing line 9a that is
oriented in a radial direction of the stator core 1 so as to pass through the center
of curvature (center of rotation) of the yoke 3.
[0025] The circumferentially deformable part 14 is formed on the radially outer peripheral
side of the yoke 3 and includes the outermost periphery of the yoke, and the circumferentially
deformable part is annularly formed with a radial width of the circumferentially pressed
divided parts 9 in a circumferential direction. The circumferentially deformable part
14 compressively deforms in the circumferential direction by the shrink-fitting of
the stator core 1 into the inner peripheral side of the motor case 7 as will be described
later.
[0026] The dividing line 9a is oriented in the radial direction through a tooth 5. In the
present embodiment, an extension line of the dividing line 9a is set so as to pass
through a center of the tooth 5 in a width direction thereof and a center of the stator
core 1. The circumferentially pressed divided part 9 has divided surfaces pressed
against each other in the circumferential direction by the tightening interference
and includes the outermost periphery of the yoke 3.
[0027] The circumferentially facing divided parts 11 are provided on a radially inner peripheral
side of the yoke 3 and each have a dividing line 11a that reaches a portion between
teeth 5 and is oriented in the radial direction of the stator core 1. Accordingly,
the dividing line 11a is oriented in the radial direction through the portion between
the teeth 5. According to the present embodiment, an extension line of the dividing
line 11a is set so as to pass through a center between the teeth 5 and the center
of the stator core 1. The circumferentially facing divided parts 11 each have divided
surfaces facing each other without a gap between them in the circumferential direction
and the circumferentially facing divided parts 11 are shifted relative to the circumferentially
pressed divided parts 9 in the circumferential direction.
[0028] The radially facing divided parts 13 are formed at a center between the radially
inner and outer sides of the yoke 3 along the circumferential direction at a predetermined
interval, and each have a dividing line 13a that is oriented in the circumferential
direction. According to the present embodiment, the dividing line 13a is formed in
an arc shape with a center of curvature that is the center of the stator core 1. The
radially facing divided parts 13 are continuous at one ends with the respective circumferentially
facing divided parts 11 and at the other ends with the respective circumferentially
pressed divided parts 9.
[0029] Accordingly, the radially facing divided part 13 connects between the circumferentially
pressed divided part 9 and the circumferentially facing divided part 11 in the circumferential
direction and has divided surfaces facing each other in the radial direction.
[0030] The radially facing divided parts 13 may be formed with a radial gap between divided
surfaces and, in this case, the divided surfaces may be also formed to be straight.
[0031] Radial lengths of the circumferentially pressed divided parts 9 and the circumferentially
facing divided parts 11 are the same in the present embodiment. A compressive stress
acting on the circumferentially facing divided part 11 is smaller than a compressive
stress on the circumferentially pressed divided part 9, or is zero. According to the
present embodiment, the compressive stress acting on the circumferentially facing
divided parts.
[Stator Core Manufacturing Method]
[0032] Fig. 4 is a process chart illustrating a stator core manufacturing method. Fig. 5
is a front main part view illustrating stator core segments processed in a segment
processing step, and Fig. 6 is a front main part view illustrating the stator core
segments in a joined state before shrink-fitting in an assembly step.
[0033] As illustrated in Fig. 4, the stator core manufacturing method according to the present
embodiment comprises a segment processing step S 1 and an assembly step S2, for manufacturing
the stator core 1 for a motor.
[0034] The segment processing step S1 forms a plurality of stator core segments 1a... in
the circumferential direction that are divided as illustrated in Fig. 5 with the circumferentially
pressed divided parts 9, the circumferentially facing divided parts 11, and the radially
facing divided parts 13 in Fig. 1. The stator core segments 1a... each have a yoke
correspondent 3aa and a tooth correspondent 5a, and divided surfaces 1aa, 1ab, 1ac,
1ad, 1ae, and 1af. The divided surfaces 1ab and 1ae are formed in an arc shape in
accordance with the dividing line 13a.
[0035] In the assembly step S2, the plurality of stator core segments 1a... are annularly
joined together in the circumferential direction. In this joined state before the
shrink-fitting, the divided surfaces 1aa and 1ad are in contact with each other in
the circumferential direction and the divided surfaces 1ab and 1ae are in contact
with each other in the radial direction, to form a gap G between the divided surfaces
1ac and 1af as illustrated in Fig. 6. The gap G is approximately 50µm according to
the present embodiment. The gap G, however, is sufficient to allow a stress acting
on the circumferentially facing divided part 11 to be put into a state of the compressive
stress being smaller than the compressive stress acting on the circumferentially pressed
divided part 9 or being zero due to the tightening interference.
[0036] Thereafter, a plurality of sets of the annularly joined stator core segments 1a...
are stacked one on another in a thickness direction thereof and attached to the inner
periphery of the motor case 7 by shrink-fitting with the radially inwardly tightening
interference.
[0037] After completion of this attachment by shrink-fitting, the divided surfaces of the
respective circumferentially pressed divided parts 9 are pressed against each other
by the tightening interference. A circumferential distortion caused by the pressing
is absorbed by moving the divided surfaces 1ab and 1ae of the respective radially
facing divided parts 13 relative to each other in the circumferential direction so
that the divided surfaces 1 ac and 1af of the respective circumferentially facing
divided parts 11 face each other in the circumferential direction without a gap as
illustrated in Fig. 1.
[Magnetic Flux]
[0038] In the stator core 1 according to the present embodiment, the compressive stress
is generated in the circumferentially pressed divided parts 9, and the compressive
stress on an inner diameter side relative to the radially facing divided parts 13
is zero.
[0039] As a result, there is no increase in iron loss on the inner diameter side relative
to the radially facing divided parts 13, and magnetic flux passes efficiently from
the teeth 5 through the circumferentially facing divided parts 11.
[Effects of the First Embodiment]
[0040] According to the first embodiment of the present invention, the stator core 1 for
the motor includes an annular yoke 3 and teeth 5 protruding radially inward from the
inner periphery of the yoke 3 and the outer periphery of the yoke 3 is attached to
the inner periphery of the motor case 7 by shrink-fitting with the radially inwardly
tightening interference. The stator core 1 comprises the circumferentially deformable
part 14 that is formed on the radially outer peripheral side of the yoke 3 and has
the circumferentially pressed divided parts 9 each having the dividing surfaces 1aa
and 1ad pressed against each other in the circumferential direction by the tightening
interference; the circumferentially facing divided parts 11 formed on the radially
inner peripheral side of the yoke 3, each having the dividing line 11a that is oriented
in the radial direction and reaches the portion between teeth 5, and having the divided
surfaces 1ac and 1af that face each other without a gap; and the radially facing divided
parts 13 formed at the center or at a portion closer to the outer periphery or elsewhere
between the radially inner and outer sides of the yoke 3 along the circumferential
direction at the predetermined interval, and each having the divided surfaces 1ab
and 1ae that face each other in the radial direction, and being continuous at one
ends with the respective circumferentially facing divided parts 11 and at the other
ends with the respective circumferentially pressed divided parts 9, the divided surfaces
1ab and 1ae moved relative to each other in the circumferential direction by the compressive
deformation of the circumferentially deformable part 14. The circumferentially facing
divided parts 11 are in a state of the compressive stress being smaller than the compressive
stress acting on the circumferentially pressed divided parts 9 or being zero.
[0041] As a result, the magnetic flux is efficiently passed from the teeth 5 through the
circumferentially facing divided parts 11 as mentioned above, thereby enhancing the
output efficiency of the motor.
[0042] In the case of the above-described conventional one of a slit type, it is physically
difficult to eliminate the slits. In the present embodiment, even if dimensions are
relatively rough by setting the circumferentially pressed divided parts 9 and the
circumferentially facing divided parts 11 in a stepped shape, the divided surfaces
of the respective circumferentially facing divided parts 11 easily face each other
without a gap in zero compressive stress due to the circumferential distortion from
the circumferentially pressed divided parts 9 to the circumferentially facing divided
parts 11. This securely improves the output efficiency of the motor.
[0043] The circumferentially pressed divided parts 9 includes the outermost periphery of
the yoke 3.
[0044] Accordingly, the circumferentially pressed divided parts 9 can be provided on the
an outermost peripheral side, thereby allowing the circumferentially facing divided
parts 11 to be formed surely on the inner peripheral side.
[0045] The dividing lines 9a and 11a are oriented to the center of the curvature of the
yoke 3.
[0046] Accordingly, the divided surfaces of the circumferentially pressed divided parts
9 are securely pressed by the tightening interference of the shrink-fitting, the divided
surfaces of the radially facing divided parts 13 easily face each other without a
gap, and the circumferentially facing divided parts 11 are securely formed with less
magnetic resistance and less iron loss.
[0047] The radial lengths of the circumferentially pressed divided parts 9 and the circumferentially
facing divided parts 11 are the same.
[0048] As a result, compressive force by the shrink-fitting is received by the pressed divided
surfaces of the circumferentially pressed divided parts 9, thereby making the divided
surfaces of the radially facing divided parts 13 face each other without a gap.
[0049] The dividing lines 9a of the circumferentially pressed divided parts 9 are oriented
in the radial direction through the respective teeth 5 and the dividing lines 11a
of the circumferentially facing divided parts 11 are oriented in the radial direction
through the respective portions between the teeth 5.
[0050] As a result, the circumferentially pressed divided parts 9 can be formed without
dividing the teeth 5.
[0051] The stator core manufacturing method includes the segment processing step S1 of forming
the plurality of stator core segments 1a... in the circumferential direction divided
at the circumferentially pressed divided parts 9, the circumferentially facing divided
parts 11, and the radially facing divided parts 13; and the assembly step S2 of joining
the plurality of stator core segments 1a... annularly in the circumferential direction
and attaching the plurality of stator core segments to the inner periphery of the
motor case 7 with the radially inwardly tightening interference, thereby pressing
the divided surfaces 1aa and 1ad of the respective circumferentially pressed divided
parts 9 against each other and facing the divided surfaces 1ac and 1af of the respective
circumferentially facing divided parts 11 without a gap between them.
[0052] Accordingly, through the segment processing step S1 and the assembly step S2, the
stator core 1 that is provided with the circumferentially pressed divided parts 9,
the circumferentially facing divided parts 11, and the radially facing divided parts
13 is securely formed.
[0053] Fig. 7 is a front main part view illustrating a stator core according to a modification.
In a stator core 1A, radial lengths of circumferentially pressed divided parts 9A
are formed relatively short, and radial lengths of circumferentially facing divided
parts 11A are formed relatively long.
[0054] Accordingly, the radial lengths of the circumferentially facing divided parts 11
A that involve compressive stress being smaller than compressive stress acting on
the circumferentially pressed divided parts 9A or being zero are enlarged. The circumferentially
deformable part 14A has an increased deformability due to a reduced width in a radial
direction, and further reduces magnetic resistance, prevents the increase in iron
loss.
SECOND EMBODIMENT
[0055] Figs. 8 to 10 are drawings according to a second embodiment of the present invention,
in which Fig. 8 is a front main part view illustrating a stator core, Fig. 9 is a
side view illustrating a flexible portion of the stator core, and Fig. 10 is a sectional
view partly illustrating a stack of the stator cores. The basic structure according
to the present embodiment is the same as that of the first embodiment, and the same
parts will be represented with the same numerals and corresponding parts will be represented
with the same numerals with "B" to omit duplicate description.
[0056] The stator core 1B according to the present embodiment, as illustrated in Figs. 8
to 10, is provided with flexible portions 15 adjoining respective circumferentially
pressed divided parts 9B in a circumferentially deformable part 14B for securing an
amount of deformation in a circumferential direction. The flexible portions 15 have
a convex-concave portion in a thickness direction of a yoke 3B. According to the present
embodiment, the convex-concave portions of the flexible portions 15 have a triangular
chevron shape in the thickness direction in a cross section. The sectional shape of
each flexible portion 15 is formed so that, when the stator cores 1 B are stacked,
the flexible portions are closely stacked one on another, or, when producing the stack,
the flexible portions are closely stacked under pressure.
[0057] As illustrated in Fig. 10, a yoke 3Ba of the stator core 1Ba at an end has a cutout
17 formed to escape an adjacent flexible portion 15.
[0058] Accordingly, the present embodiment also provides the same effects as the first embodiment
due to the presence of the circumferentially pressed divided parts 9B, the circumferentially
facing divided parts 11B, and the radially facing divided parts 13B. Furthermore,
in the present embodiment, since the amount of compression of the circumferentially
pressed divided parts 9B due to the shrink-fitting is increased by the flexible portions
15, gaps formed in the circumferentially facing divided parts 11B before the shrink-fitting
is set to, for example, approximately 70µm to facilitate the setting of the gaps.
[0059] Fig. 11 is a side view illustrating a flexible portion of a stator core according
to a modification, and Fig. 12 is a sectional view partly illustrating a stack of
the stator cores of according to the modification. The basic structure of the modification
is the same as that of the example in Figs. 8 to 10, and the same parts will be represented
with the same numerals and corresponding components will be represented with the same
characters with "C" omit duplicate description.
[0060] In a stator core 1C of Figs. 11 and 12, a convex-concave portion of a flexible portion
15C provided in a circumferentially deformable part 14C has a triangular chevron shape
in a thickness direction in a cross section so that the convex-concave portion protrudes
both forward and rearward in a direction along an axis of the stator core 1C. The
yokes 3Ca and 3Cb of stator cores 1Ca and 1Cb at both ends have cutouts 17Ca and 17Cb
formed in a shape to escape adjacent flexible portions 15C.
[0061] With this modification, the amount of deformation of the flexible portions 15C is
further increased relative to the example in Figs. 8 to 10, thereby further easily
setting gaps in the circumferentially facing divided parts (corresponding to the circumferentially
facing divided parts 11B of Fig. 8).
[0062] Fig. 13 is a side view illustrating a flexible portion of a stator core according
to another modification and Fig. 14 is a sectional view partly illustrating a stack
of the stator cores according to the modification. The basic structure of the modification
is the same as that of the example in Figs. 8 to 10, and the same parts will be represented
with the same characters and corresponding parts will be represented with the same
numerals with "D" to omit duplicate description.
[0063] In a stator core 1D of Figs. 13 and 14, a convex-concave portion of a flexible portion
15D provided in a circumferentially deformable part 14D has a curved chevron shape
in a thickness direction in a cross section. A yoke 3Da of the stator core 1Da at
an end has a cutout 17D formed in a shape to escape an adjacent flexible portion 15D.
[0064] Accordingly, the modification provides substantially the same effects as the example
of Figs. 8 to 10.
[0065] Fig. 15 is a side view illustrating a flexible portion of a stator core according
to still another modification and Fig. 16 is a sectional view partly illustrating
a stack of the stator cores according to the modification. In a stator core 1E of
Figs. 15 and 16, a convex-concave portion of a flexible portion 15E provided in a
circumferentially deformable part 14E has a curved chevron shape in a thickness direction
in a cross section so that the convex-concave portion protrudes both forward and rearward
in a direction along an axis of the stator core 1E. The yokes 3Ea and 3Eb of stator
cores 1Ea and 1Eb at both ends have cutouts 17Ea and 17Eb formed in a shape to escape
adjacent flexible portions 15E. The modification provides substantially the same effects
as the modification of Figs. 11 and 12.
THIRD EMBODIMENT
[0066] Figs. 17 to 19 are drawings according to a third embodiment of the present invention
in which Fig. 17 is a front main part view illustrating a state of a stator core attached
to a motor case by shrink-fitting, Fig. 18 is a process chart illustrating a stator
core manufacturing method, and Fig. 19 is a front main part view illustrating a state
of a semi-finished stator core before the shrink-fitting. The basic structure of the
present embodiment is the same as that of the first embodiment, and the same parts
will be represented with the same numerals and corresponding components will be represented
with the same numerals with "F" to omit duplicate description.
[0067] As illustrated in Fig. 17, a stator core 1F of the present third embodiment is provided
with a circumferentially deformable part 14F having no circumferentially pressed divided
parts and is a circumferentially continuous ring part. A radially facing divided parts
13F are continuous at one ends with respective circumferentially facing divided parts
11 and closed at the other ends.
[0068] As illustrated in Fig. 18, a stator core manufacturing method according to the present
embodiment has a semi-finished core processing step S10 and an assembly step S 11,
for producing a stator core 1 F for a motor.
[0069] In the semi-finished core processing step S10, a semi-finished core 1Fa illustrated
in Fig. 19 is formed. The semi-finished core 1Fa is provided with circumferentially
facing divided part correspondents 11Fa, radially facing divided part correspondents
13Fa, a circumferentially deformable part correspondent 14Fa, and teeth correspondents
5a, and divided surfaces 1ab, 1ae, 1ac, and 1af.
[0070] The circumferentially facing divided part correspondents 11Fa, the radially facing
divided part correspondents 13a, the circumferentially deformable part correspondent
14Fa, and the teeth correspondents 5a correspond to the circumferentially facing divided
parts 11, the radially facing divided parts 13F, the circumferentially deformable
part 14F, and the teeth 5 in Fig. 17.
[0071] As illustrated in Fig. 19, the semi-finished core 1Fa before shrink-fitting has a
gap G between the divided surfaces 1ac and 1af. This gap G is approximately 50µm in
the present embodiment. The requirements for the gap G are as mentioned above.
[0072] In the assembly step S11 of Fig. 18, semi-finished cores 1Fa... of Fig. 19 are stacked
one on another in a thickness direction and attached to an inner periphery of a motor
case 7 of Fig. 17 by shrink-fitting with a radially inwardly tightening interference.
[0073] After completion of this attachment by the shrink-fitting, the circumferentially
deformable part correspondent 14Fa of Fig. 19 is compressed in a circumferential direction
due to the tightening interference. A circumferential distortion caused by this compression
is absorbed by moving the divided surfaces 1ab and 1ae of the respective radially
facing divided part correspondents 13Fa relative to each other in the circumferential
direction, thereby making the divided surfaces 1ac and 1af of the respective circumferentially
facing divided parts 11 face each other without a gap as illustrated in Fig. 17.
[0074] Accordingly, in the present embodiment, the circumferentially facing divided parts
11 can be put into a state of compressive stress being smaller than compressive stress
acting on the circumferentially deformable parts 9 or being zero, thereby providing
the same effects as the first embodiment.
[0075] Furthermore, since the semi-finished core 1Fa is not divided, it is easy to handle
and reduces the number of parts for easy assembly and easy parts control.
[0076] Incidentally, the present embodiment may also form flexible portions on an outer
peripheral side or elsewhere relative to the radially facing divided parts 13F, thereby
facilitating the compressive deformation of the circumferentially deformable part
14F.
[0077] The radial width of the circumferentially deformable part 14F may be relatively narrow
and the radial length of the circumferentially facing divided parts 11 may be relatively
long. In this case, the compressive deformation of the circumferentially deformable
part 14F by the tightening interference can be made easier.
[0078] Fig. 20 is a front main part view illustrating a state of a stator core according
to a modification of the third embodiment attached to a motor case by shrink-fitting.
[0079] In this modification, dividing lines 13a of radially facing divided parts 13F are
set to be inclined so that one ends of the dividing lines continuous to respective
circumferentially facing divided parts 11 are located on an inner peripheral side
relative to the other closed ends. Accordingly, when divided surfaces of the radially
facing divided part 13F move relative to each other in a circumferential direction
by compressive deformation at the time of shrink-fitting, the divided surfaces come
in closely contact with each other.
[0080] Even if the divided surfaces of the radially facing divided part 13F do not come
in closely contact with each other by the compressive deformation at the time of the
shrink-fitting, the gap between the divided surfaces can be minimized to improve magnetic
properties.
[0081] Incidentally, such setting of the dividing line 13a is also equally applicable to
the stator cores 1, 1B, 1C, 1D, and 1E of the first and second embodiments.
DESCRIPTION OF NUMERALS
[0082]
1, 1B, 1C, 1D, 1E, 1F stator core
1Fa semi-finished core
1a... stator core segments
1aa, 1ab, 1ac, 1ad, 1ae, 1af divided surface
3, 3A, 3B, 3C, 3D, 3E yoke
5 tooth
5a tooth correspondent
7 motor case (annular member)
9, 9A, 9B, 9C, 9D, 9E circumferentially pressed divided part
9a, 11a, 13a dividing line
11 circumferentially facing divided part
11F circumferentially facing divided part correspondent
13, 13F radially facing divided part
13F radially facing divided part correspondent
14, 14A, 14B, 14C, 14D, 14E, 14F circumferentially deformable part
14Fa circumferentially deformable part correspondent
15, 15C, 15D, 15E flexible portion
S 1 segment processing step
S2, S11 assembly step
S10 semi-finished core processsing step
1. A stator core for a motor including an annular yoke and teeth protruding radially
inward from an inner periphery of the yoke, an outer periphery of the yoke attached
to an inner periphery of an annular member with a radially inwardly tightening interference,
comprising:
a circumferentially deformable part formed on a radially outer peripheral side of
the yoke and compressively deformed in a circumferential direction by the tightening
interference;
circumferentially facing divided parts formed on a radially inner peripheral side
of the yoke, and each having a dividing line that is oriented in a radial direction
and reaches a portion between the teeth and divided surfaces that face each other
without a gap; and
radially facing divided parts formed between the radially inner and outer sides of
the yoke along the circumferential direction at a predetermined interval, each having
divided surfaces that face each other in the radial direction, and being continuous
at one ends with the respective circumferentially facing divided parts, the divided
surfaces moved relative to each other in the circumferential direction by compressive
deformation of the circumferentially deformable part, wherein
the circumferentially facing divided parts are in a state of a compressive stress
being smaller than a compressive stress acting on the circumferentially deformable
part or being zero.
2. The stator core according to claim 1, wherein:
the circumferentially deformable part has circumferentially pressed divided parts
each having a dividing line oriented in the radial direction and divided surfaces
pressed against each other by the tightening interference and being continuous with
respective other ends of the circumferentially facing divided parts.
3. The stator core according to claim 1, wherein:
the circumferentially deformable part is a ring part continuous in the circumferential
direction.
4. The stator core according to any one of claims 1 to 3, wherein:
the circumferentially deformable part includes an outermost periphery of the yoke.
5. The stator core according to any one of claims 1 to 4, wherein:
the dividing lines of the circumferentially facing divided parts are oriented to a
center of the yoke.
6. The stator core according to claim 2, wherein:
radial lengths of the circumferentially pressed divided parts and the circumferentially
facing divided parts are the same.
7. The stator core according to claim 2, wherein:
radial lengths of the circumferentially pressed divided parts are shorter than radial
lengths of the circumferentially facing divided parts.
8. The stator core according to claim 2, wherein:
the dividing lines of the circumferentially pressed divided parts are oriented in
the radial direction through the respective teeth; and
the dividing lines of the circumferentially facing divided parts are oriented in the
radial direction through the respective portions between the teeth.
9. The stator core according to any one of claims 1 to 8, wherein:
the circumferentially deformable part has a flexible portion for securing an amount
of the deformation in the circumferential direction.
10. The stator core according to claim 9, wherein:
the flexible portion is a convex-concave portion in a thickness direction of the yoke.
11. The stator core according to any one of claims 1 to 10, wherein:
dividing lines of the radially facing divided parts are set to be inclined so that
one ends continuous with the circumferentially facing divided parts are located on
an inner peripheral side relative to other ends being closed.
12. A stator core manufacturing method for manufacturing the stator core for a motor according
to claim 2, comprising:
a segment processing step of processing a plurality of circumferential stator core
segments divided at the circumferentially pressed divided parts, the circumferentially
facing divided parts, and the radially facing divided parts; and
an assembly step of joining the plurality of stator core segments annularly in the
circumferential direction and attaching the plurality of stator core segments to the
inner periphery of the annular member with the radially inwardly tightening interference,
thereby pressing the divided surfaces of the respective circumferentially pressed
divided parts against each other and facing the divided surfaces of the respective
circumferentially facing divided parts without a gap in the circumferential direction.
13. A stator core manufacturing method for manufacturing the stator core for a motor according
to claim 3, comprising:
a semi-finished core processing step of forming a semi-finished stator core having
the ring part, circumferentially facing divided part correspondents, and radially
facing divided part correspondents; and
an assembly step of attaching the semi-finished stator core to the inner periphery
of the annular member with the radially inwardly tightening interference, thereby
causing compressive deformation of the ring part and facing the divided surfaces of
the respective circumferentially facing divided parts without a gap in the circumferential
direction.
14. The stator core manufacturing method according to claim 12 or 13, wherein:
the attachment to the annular member with the tightening interference is carried out
by shrink-fitting.